Power hammer



F. SCHNEIDER POWER HAMMER Filed Jan. 27, 1928 between the relatively mova Patented Aug. 20, 1929.

UNITED STATES PATENT OFFICE.

FRANKLIN SCHNEIDER, 0F CLEVELAND, OHIO, ASSIGNOR TO VAN DORN ELECTRIC TOOL COMPANY, OF CLEVELAND,

OHIO, A CORPORATION OF OHIO.

POWER HAMMER.

Application filed January 27, 1928. Serial No. 249,931.

This invention relates to power hammers, and more particularly to that type in which rapidly repeated blows are imparted to a longitudinally movable striker by the impacts on the anvil portion thereof of a hammer member carried by a rotatable body or carrier which turns continuously in the same direction. The invention is an improvement upon the construction described, shown and claimed in the patent to Rasch, No. 1,579,840, April 6, 1926.

In such hammers, the hammer member oscillates in a chamber in the rotating carrier or driver and is a fairly close fit in said chamber to take advantage of the air cushioning effect. As a consequence, any dirt or foreign material lodging on the walls of the chamber or the surface of the hammer interferes with smooth and proper operation and may even stop oscillation of the hammer and prevent rotation of the carrier so as to stop tool operation.

The present invention has for its object to provide means for producin a close seal or fit hie surfaces of the hammer and carrier, but permitting free and easy relative motion therebetween, all in a manner to keep the surfaces lubricated and clean and free from foreign material which might impede operation, and at the same time take full advantage of the air cushioning effect.

In the drawings, Fig. 1 is a longitudinal sectional view through one form of hammer embodying the invention; Fig. 2 is a sectional elevation on the line 22, Fig. 1, through the carrier and hammer members; and Fig. 3 is a detail view of the packing device.

The hammer shown in the drawings comprises a casing or body 1 provided with a chamber in which rotates the carrier 2 about the central axis 3, said carrier being generally of cylindrical form and driven in any suitable manner, such as by a flexible shaft or by direct connection to a motor, either electric, air, or of any other type, which may be mounted in the same casing with the rest of the tool, as will be readily understood. The particular manner of driving the carrier forms no part of the present invention.

In the carrier 2, and on an axis 4 eccentric to the center axis 3, is pivoted the hammer member 5, said member being, generally speaking, of the form of a sector of a cylinder bounded by two parallel end surfaces 6 and an outer cylindrical surface 7. Said hammer oscillates about the axis 4 in a chamber 8, with its end and cylindrical walls 6, 7 moving in fairly close neighboring relation with the walls of the chamber 8. One end of the hammer is formed to provide a striking face 9 adapted to engage one end of the striker 10 and through the latter imparta blow either to a tool mounted in a suitable socket or to the work, as will be readily understood.

The carrier tool rotates in a counter-clockwise direction, Fig. 1. At the moment of impact the hammer 5 occupies the position shown and is fully extended from its chamher, but its rear end portion or heel still lies partially within the chamber so that the hammer is never fully obtruded or projected therefrom. Upon impact, the hammer rebounds and recedes in the chamber so that the carrier can pass the striker and come around through another revolution to impart a second impact, etc.

According to the present invention, one or the other of the surfaces, either of the hammer body or of the walls of the chamber of the carrier in which it turns, or both, is provided with packing means preferably more or less adjustable or self-accommodating and arranged to wipe over the companion surfaces along which it travels and maintain a tight seal or fit and automatically clean said surfaces to free the same from dirt or foreign matter which may find lodgement thereon. In the specific embodiment shown, the hammer body 5 is provided with grooves or channels in both its end and cylindrical surfaces. The end grooves 11 extend practically radially and at their outer ends communicate with the groove 12 in the cylindrical surface, which is parallel to the axis 4:, so that the three grooves together are of U-form. In said grooves is located a packing member 13 of U- form, shown in detail in Fig. 3. It is backed by yielding means, such as the compression springs 14 lying in openings in the hammer body. This packing member 13 may be made of any suitable material capable of withstanding considerable wear due to the friction, and also the heat generated in operation. One suitable material for the purpose is phenol formaldehyde condensation product, or some fibrous material impregnated therewith, or other materials used for noiseless gears.

In operation the packing member functions somewhat like a piston ring in that it travels back and forth with the hammer member along the surfaces of the chamber in the carrier. Of eourse, the parts are lubricated with oil or like material, and the wiping action of the packing member distributes the lubricant along the surfaces, keeping them smooth and reducing friction, and at the same time the packing member pushes out of the way any foreign material which might find lodge ment.

The chamber in the 'carrier is, of course, vented with a relief port, as is usual in these devices, but no particular reference to such relief is necessary herein. 7

What I claim is: I

1. A power hammer, comprising a casing, a carrier member rotatable therein and provided with a chamber, a hammer member oscillating in said chamber on an axis eccentric to the axis of rotation of the carrier member, a striker actuated thereby, the hammer member having surfaces travelling along contiguous surfaces of the chamber of the carrier member, and a packing member on the surface of one of said members adapted to travel along the surface of the other memher and free the same from foreignmaterial.

2. A power hammer, comprising a casing,

. a carrier-memberrotatable therein and provided with a chamber, a hammer member oscillating in said chamber on an axis eccentric to the axis of rotation of the carrier member, a striker actuated thereby, and yieldable means for cleaning the surface of one of said members by the travel of the other member along the same. i

3. A power hammer, comprising a casing, a carrier rotatable therein and provided with a chamber, a hammer member oscillating in said chamber on an axis eccentric to the axis of the carrier member, a striker actuated thereby, and a yielding packing member mounted in a recess in the hammer member and adapted to travel along a surface of the chamber oft-he carrier member.

4. A power hammer, comprising a casing, a carrier rotatable therein and provided with a chamber, a hammer member oscillating in said chamber on an axis eccentric to the axis of the carrier member, a striker actuated signature. 7

, FRANKLIN SCHNEIDER. 

